1. **Stating the problem:** Identify which compound among H2, O2, NH4+, F2, and HCl contains a coordinate covalent bond. 2. **Understanding coordinate covalent bonds:** A coordinate covalent bond (also called a dative bond) occurs when one atom donates both electrons to form a shared pair in a bond. 3. **Analyzing each compound:** - H2: A simple covalent bond with each hydrogen sharing one electron. - O2: A double covalent bond with shared electrons, no coordinate bond. - NH4+ (ammonium ion): Formed when NH3 donates a lone pair to H+, creating a coordinate covalent bond. - F2: A single covalent bond with shared electrons, no coordinate bond. - HCl: A polar covalent bond, no coordinate bond. 4. **Conclusion:** The compound with a coordinate covalent bond is **NH4+**. **Final answer:** NH4+